Sterilization pouch with internal and external indicators

ABSTRACT

A sterilization package includes a first package layer and a second package layer coupled to the first package layer with a perimeter seal extending around a portion of the sterilization package to define a pouch having a proximal end and a distal end. A first sterilization indicium is disposed on the second package layer exterior of the pouch and a second sterilization indicium is disposed on the second package layer interior of the pouch. The first and second sterilization indicia are multi-parameter sterilization indicia configured to be responsive to a sterilization process such that the first and second sterilization indicia undergo a visual change to a desired ending color when the package is subjected to complete multi-parameter sterilization conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of application Ser. No. 12/351,427,filed Jan. 9, 2009, entitled “STERILIZATION POUCH WITH INTERNAL ANDEXTERNAL INDICATORS,” which claims the benefit of ProvisionalApplication No. 61/021,104, filed Jan. 15, 2008, each of which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

This invention relates to the field of sterilizable packaging usingcolor-changing indicators to display the sterilization status thereof.

BACKGROUND

In the past, packages such as pouches were used to retain contents formedical or veterinary or dental applications and to enable sterilizationthereof, with an indication of whether the packaging had undergonesterilization. The two most popular techniques of sterilization for suchpackages are processing using either steam or ethylene oxide(hereinafter referred to as “ETO”).

In the prior art, as discussed in the “BACKGROUND” section of U.S. Pat.No. 4,091,921, it was known to apply indicator ink to the exterior ofthe package, with a color change indicating that the package was subjectto the sterilization process. Different inks were used for steam and ETOas the sterilizing medium. Indicator inks were also applied to theinterior of the package, to indicate that the interior sealed chambercontaining the contents to be sterilized was subject to at least apartial exposure to a sterilization process. U.S. Pat. Nos. 4,091,921and 5,344,017 each illustrate a prior art approach in which theindicator ink was sealed in a segregated interior compartment in thepouch to prevent the pouch contents from coming in contact with theinterior ink indicator. U.S. Pat. No. 3,093,242 relates to an internalindicator not protected from contact with the contents of the pouch. Theentire contents of each of U.S. Pat. Nos. 4,091,921, 5,344,017, and3,093,242 are expressly incorporated herein by reference.

SUMMARY

In one aspect, the present disclosure relates to a sterilization packageincluding a first package layer and a second package layer coupled tothe first package layer with a perimeter seal extending around a portionof the sterilization package to define a pouch having a proximal end anda distal end. The pouch includes a sealable opening at the proximal end.A first sterilization indicium is disposed on the second package layerexterior of the pouch and proximate the distal end of the pouch. Asecond sterilization indicium is disposed on the second package layerinterior of the pouch and proximate the distal end of the pouch. Thefirst and second sterilization indicia are on a side of the secondpackage layer facing the first package layer. The first and secondsterilization indicia are multi-parameter sterilization indiciaconfigured to be responsive to a sterilization process such that thefirst and second sterilization indicia undergo a visual change to adesired ending color when the package is subjected to completemulti-parameter sterilization conditions.

In another aspect, the present disclosure relates to a method for makinga sterilization package. A plurality of sterilization indicia areprinted on a first major side of a paper layer. The plurality ofsterilization indicia include first and second multi-parametersterilization indicia configured to be responsive to a sterilizationprocess such that the first and second sterilization indicia undergo avisual change to a desired ending color when the package is subjected tocomplete multi-parameter sterilization conditions. A polymer layer isbonded to the first major side of the paper layer with a perimeter seal.The perimeter seal extends around a portion of the sterilization packageto define a pouch having a proximal end with a sealable opening and adistal end. The perimeter seal is disposed between the first and secondmulti-parameter sterilization indicia at the distal end of the pouchsuch that the first multi-parameter sterilization indicium is exteriorof the pouch and the second multi-parameter sterilization indicium isinterior of the pouch.

In a further aspect, the present disclosure relates to a sterilizationpackage including a first package layer and a second package layercoupled to the first package layer with a perimeter seal extendingaround a portion of the sterilization package to define a pouch having aproximal end and a distal end. The pouch includes a sealable opening atthe proximal end. A first steam sterilization indicium is printed on thesecond package layer exterior of the pouch and proximate the distal endof the pouch. A second steam sterilization indicium is printed on thesecond package layer interior of the pouch and proximate the distal endof the pouch. The first and second steam sterilization indicia aredisposed on a side of the second package layer facing the first packagelayer. At least one of the first and second steam sterilization indiciais a multi-parameter steam sterilization indicium that is configured tochange from a first color to a second color when the sterilizationpackage is subjected to complete sterilization conditions with respectto at least two sterilization process variables selected from the groupconsisting of time, temperature, and presence of steam.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the embodiment shown in FIG.1.

FIG. 3 is a plan view of a second embodiment of the present invention.

FIG. 4 is a plan view of a third embodiment of the present invention.

FIG. 5 is a plan view of a fourth embodiment of the present invention.

DETAILED DESCRIPTION

Referring to the Figures and most particularly to FIGS. 1 and 2, asterilizable package 10 in the form of a pouch 12 useful in the practiceof the present invention may be seen. Pouch 12 preferably has a firstlayer 14 preferably formed of a polyester/polypropylene film bonded to asecond layer 16 preferably formed of kraft paper. The bond is formed bya perimeter seal 18 (such as by heat sealing) preferably extendingaround 3 of the 4 sides of layers 14 and 16 to form the pouch 12 with aninitially open end 20, formed by an open edge 22 of the layer 14 notbonded to layer 16. Layer 16 may be perforated along a fold line 24 andpreferably has a strip of contact adhesive 26 along open end 20. Arelease layer 28 initially covers the strip of adhesive 26.

In the practice of the present invention, a pair of first indicia 30, 32make up the first indicator and are located on the package 10 andexterior of the pouch 12; and a pair of second indicia 34, 36 make upthe second indicator and are located on the package 10 and interior ofthe pouch 12. It is to be understood that the locations of each of thefirst indicia 30 and 32 may be interchanged; similarly the locations ofthe second indicia 34 and 36 may be interchanged. As shown, there is onepair of indicia 30, 32 making up the first indicator and another pair ofindicia 34, 36 making up the second indicator. One indicium (for exampleindicium 30) of the first indicator and one indicium (for exampleindicium 34) of the second indicator may each be responsive tomulti-parameter steam sterilization, and the other indicium (for exampleindicium 32) of the first indicator and the other indicium (for exampleindicium 36) of the second indicator are each responsive to gassterilization. The gas is preferably ethylene oxide. The package 10 maythus be seen to include first and second indicators, each of whichinclude a separate indicium for indicating the results of one of steamand gas sterilization, with at least the steam sterilization responsiveindicium 34 of the second indicator being a multi-parameter responsivesteam sterilization indicium. Preferably both indicia 30 and 34 areresponsive to multi-parameter steam sterilization. Each of the indicia32, 36 may be responsive to multi-parameter gas (such as ethylene oxide)sterilization, as well. Alternatively, the indicia 32 and 36 may undergoa color change simply in response to some exposure to a sterilizing gasmedium such as ethylene oxide.

The package 10 may be the same as is used in pouches available fromMedi-Plus Laboratories, division of Cur Med Healthcare Packaging ofChicago, Ill., and marketed as a Self-Seal Pouch by Medi-PlusLaboratories. Alternatively, the package 10 may be the same orsubstantially equivalent to the ProView Sterilization Pouch marketed byCottrell, Ltd, of Englewood Colo. Neither Medi-Plus nor Cottrell offerpouches that have both process external and multi-parameter internalindicators, however.

The chemical indicators may be in the form of indicia formed by inkprinted on one of the layers 14 and 16, preferably layer 16. Theseindicia undergo a visibly perceptible color change to a desired endingcolor to indicate that successful sterilization has occurred at theindicator.

Specifically, in one embodiment, the steam sterilization processindicator changes color from one designated initial color (for example,pink) to another, readily distinguishable color (for example, dark brownmay be the desired ending color) upon sufficient exposure to completesterilization conditions (i.e., when exposed to a completemulti-parameter steam sterilization process). The color change to thedesired ending color i.e., “designated end color change” may be causedby a chemical reaction in the ink, such as a copper or lead compoundreacting with a source of sulfur to produce copper or lead sulfide atthe indicia.

Also, in one embodiment, the ETO (ethylene oxide) process indicatorchanges color from one designated initial color (for example, ablue/grey) to another designated, readily distinguishable color (forexample, a gold/brown may be the desired ending color). The color changefrom blue/grey (as the desired starting color) to gold/brown (as thedesired ending color) may be achieved by a pyridine derivativeacetylated in a direct reaction with the ETO.

Preferably, the minimum process conditions necessary to cause completecolor change (corresponding to “successful sterilization”) resulting inachieving the desired ending color in the multi-parameter sterilizationprocess are as follows:

For the steam process sterilization: 10 minutes exposure to steam at250° F.

For ETO: 60 minutes exposure to ETO at 8 psi and 135° F.

It may be noted that there may be some color change in the steam processindicia with longer periods of exposure below 250° F. or with shorterperiods of exposure at temperatures greater than 250° F. Similarly, somecolor change may be observed for the ETO process indicia with extendedexposure at normal room ambient temperatures, and with times as low as15 minutes with elevated temperature/pressure, and at pressures as lowas normal atmospheric ambient pressures with extended time/elevatedtemperatures. However, when the package or pouch is subjected to onlyincomplete or insufficient sterilization process conditions in thepractice of the present invention, the internal multi-parametersterilization process indicium will not change to the desired endingcolor.

In the practice of the present invention, it has been found preferableto include an independent barrier seal 38 in the form of a bar 40blocking contact by a conventional medical device (not shown) whenplaced in the interior 42 of the pouch 12 with either of the internalindicators or indicia 34 or 36. Bar 40 is preferably not connected toperimeter seal 18. This has the advantage of preventing contamination ofthe pouch contents with the ink and also permitting the internalindicators to be in the same compartment as the pouch contents beingsterilized. The steam or gas present in the pouch interior 42 is allowedto reach the indicators 34, 36.

To use the package 10 as a pouch for sterilization, contents (such as amedical device) are placed in the pouch interior 42, by insertion pastthe open edge 22 of the first layer 14. The release layer 28 is thenremoved, and the second layer 16 is folded along fold line 24 to presentadhesive region 26 against the first layer, sealing the open end 20 ofthe pouch 12.

It is to be understood that the indicators 30 and 32 may be locatedunder respective corners of the first layer 14, however, in the practiceof the present invention, the first layer is not secured to the secondlayer in the corners where indicators 30 and 32 are located, thuspresenting indicators to the external environment in which package 10 islocated.

Once the package 10 is sealed as described above, it is preferablyplaced in an appropriate sterilization chamber (not shown) and desirablyexposed to the appropriate sterilization process, which may be eithersteam or gas (such as ETO) at the appropriate conditions and for theappropriate time for that sterilization process.

Both the external and internal indicators undergo a visually perceptiblechange to the desired ending color when the package is subjected tocomplete sterilization conditions. However, when steam is thesterilizing medium, only the first (external) indicator may undergo avisually perceptible change to the desired ending color when the packageis subjected to an incomplete sterilization conditions. The second(internal) indicator will not undergo a complete color change to thedesired ending color in the event the interior 42 of the pouch 12 is notsubjected to complete steam sterilization conditions, and thus a colorchange of the external indicator to the desired ending color without acolor change of the internal indicator to the desired ending color willthereafter indicate to a user that steam sterilization was attempted,but was incomplete.

In one aspect, the present invention may thus be seen to be a method ofproviding a visually perceptible indication of successful orunsuccessful exposure to a proper steam sterilization cycle for thecontents of a package of the type having a generally planar polymerlayer and a paper member joined together by a marginal seal extendingaround a portion of a perimeter of the package to form a pouch. Themethod includes providing the first indicator located on the package andexterior of the pouch; and providing the second indicator located on thepackage and interior of the pouch.

The method further includes subjecting the package to a steamsterilization process and observing the first and second indicators. Inthis method, both the first and second indicators undergo a visuallyperceptible change to a desired ending color when the package issubjected to complete sterilization conditions, but only the firstindicator may undergo a visually perceptible change to the desiredending color when the package is subjected to incomplete sterilizationconditions. The method includes having the first and second indicatorsresponsive to steam sterilization, and may include indicators responsiveto gas sterilization. The method also may include having the first andsecond indicators each with (separate) indicia responsive to steam orgas sterilization, with the preferred gas being ethylene oxide.

Examples of other shapes and sizes of pouches useful in the practice ofthe present invention may be seen in FIGS. 3-5, where like features arenumbered the same as in the embodiment shown in FIG. 1. In FIG. 1, thepouch is about 3.5 inches wide by about 5.25 inches in length; the pouchof FIG. 3 is about 2.75 inches wide by about 9 inches in length. Thepouch in FIG. 4 is about 5.25 inches wide by about 10.125 inches long.The pouch in FIG. 5 is about 7.5 inches wide by about 13.125 incheslong. Dimensions given are for the width of the layers 14 and 16, andlengths are for the length of the first or top layer 14.

The International Organization for Standardization (ISO) is a worldwidefederation of national standards entities. ISO/TC 198, Sterilization ofHealthcare Products, has developed sterilization standards for medicaldevices and related healthcare products.

In addition, AAMI standards have been recognized by the United StatesFood and Drug Administration (FDA). The applicable standard isANSI/AAMI/ISO 11140-1: 2005, “Sterilization of healthcareproducts—Chemical Indicators—Part 1: General Requirements” (Arlington,Va.: AAMI, 2005).

Single parameter chemical indicators have been developed to meet therequirements of indicating whether a particular temperature has beenreached in a medical device or packaging sterilization process.

In contrast, multi-parameter sterilization chemical indicators respondnot only to temperature, but also require sufficient time and/or thepresence of sterilizing medium such as steam or ethylene oxide toconfirm that sufficient sterilization has been achieved when a medicaldevice package has been subjected to a process intended to sterilize thecontents of the package.

The invention may thus be seen to be a sterilizable package comprising agenerally planar polymer layer and a paper member joined together by amarginal seal extending around a portion of a perimeter of the packageto form a pouch, the package comprising a first indicator located on thepackage and exterior of the pouch; and a second indicator located on thepackage and interior of the pouch such that both indicators undergo avisually perceptible change to a desired ending color when the packageis subjected to complete multi-parameter steam sterilization conditions,while, at most, only the first indicator will undergo a visuallyperceptible change to the desired ending color when the package issubjected to incomplete steam sterilization conditions. The first andsecond indicators include steam sterilization indicators and may includegas sterilization indicators, and the gas may be ethylene oxide. In oneembodiment, the first and second indicators may each comprise a separateindicia for indicating one of steam and gas sterilization, again withthe gas being ethylene oxide.

The invention may also be characterized as a method of providing avisual indication, such as a color change, of successful or unsuccessfulsteam sterilization of the contents of a package of the type having agenerally non-porous membrane such as a planar polymer layer and aporous membrane such as a paper member joined together by a marginalseal extending around a portion of a perimeter of the package andincluding an adhesive region on one of the porous and non-porousmembranes foldable against the other of the non-porous and porousmembranes to form a pouch, with the method comprising providing a firstindicator located on the package and exterior of the pouch; andproviding a second indicator located on the package and interior of thepouch; subjecting the package to a steam sterilization process; andobserving the first and second indicators wherein both the first andsecond indicators undergo a visual change to a desired ending color whenthe package is subjected to complete multi-parameter steam sterilizationconditions, while, at most, only the first indicator will undergo avisual change to the desired ending color when the package is subjectedto incomplete sterilization conditions, as measuredmulti-parametrically. The method may be further characterized whereinthe first and second indicators are responsive to steam sterilization,or to gas sterilization. The method may be further characterized by thefirst and second indicators each having indicia responsive to steam andgas sterilization. The method may be still further characterized byhaving the gas be ethylene oxide.

The invention is not to be taken as limited to all of the detailsthereof, as modifications and variations thereof may be made withoutdeparting from the spirit or scope of the invention.

1.-7. (canceled)
 8. A method for making a sterilization package, themethod comprising: printing a plurality of sterilization indicia on afirst major side of a paper layer, the plurality of sterilizationindicia including first and second multi-parameter sterilization indiciaconfigured to be responsive to a sterilization process such that thefirst and second sterilization indicia undergo a visual change to adesired ending color when the package is subjected to completemulti-parameter sterilization conditions; bonding a polymer layer to thefirst major side of the paper layer with a perimeter seal, the perimeterseal extending around a portion of the sterilization package to define apouch having a proximal end with a sealable opening and a distal end,wherein the perimeter seal is disposed between the first and secondmulti-parameter sterilization indicia at the distal end of the pouchsuch that the first multi-parameter sterilization indicium is exteriorof the pouch and the second multi-parameter sterilization indicium isinterior of the pouch.
 9. The method of claim 8, further comprising:joining a portion of the first major side of the paper layer to aportion of the polymer layer with a barrier seal proximate the secondsterilization indicium, wherein the barrier seal is not connected to theperimeter seal.
 10. The method of claim 8, wherein the first and secondindicators are configured to be responsive to a steam sterilizationprocess.
 11. The method of claim 8, wherein the first and secondindicators are configured to be responsive to a gas sterilizationprocess.
 12. The method of claim 11, wherein the first and second gassterilization indicia are configured to be responsive to ethylene oxide.13. The method of claim 8, wherein the plurality of sterilizationindicia further comprises third and fourth sterilization indicia, andwherein the perimeter seal is disposed between the third and fourthsterilization indicia at the distal end of the pouch such that the thirdsterilization indicium is exterior of the pouch and the fourthsterilization indicium is interior of the pouch. 14.-23. (canceled)